The present application relates to the field of particle concentrators, and more particularly, to improving extraction of organic, inorganic and/or biological particles concentrated by a particle concentrator employing traveling wave grids.
It is desirable to move and concentrate particles in a sample for a variety of reasons. For example such movement is useful in applications related to, among others, analysis of proteins and DNA fragment mixtures, and methodologies used for processes such as DNA sequencing, isolating active biological factors associated with diseases such as cystic fibrosis, sickle-cell anemia, myelomas, and leukemia, and establishing immunological reactions between samples on the basis of individual compounds. Movement by traveling wave grids is an extremely effective tool because, among other attributes, it does not affect a molecule's structure, is highly sensitive to small differences in molecular charge and mass, and will not damage the cells of biological materials. Thus, particle concentrators employing traveling wave grids are useful not only for micron-sized particles but also having sufficient sensitivity for molecular transport.
Traveling wave grids manipulate particles by subjecting them to traveling electric fields. Such traveling fields are produced by applying appropriate voltages of suitable frequency and phase to electrode arrays of suitable design, such that non-uniform electric fields are generated.
Thus, by use of traveling wave grids, particles are manipulated and positioned at will without physical contact, leading to new methods for focusing, separation and concentration technology. In many applications, once the particles are sufficiently concentrated, it is useful to move the concentrate sample of particles to analytical devices for investigation and experimentation.
It has been noted, however, that with existing and previously proposed particle concentrators, including both those relying on traveling wave grid technology, as well as others, once the particles are concentrated, moving the particles in the concentrated sample from the particle concentrator raises its own set of issues.
Particularly, extracting a concentrated sample of particles from a collection chamber in a traveling wave grid device built on a micro-fluidic scale, can be challenging, partly because the particles (e.g., organic, inorganic or other bio-materials) may stick to the walls of the collection chamber, or to the traveling wave surface, or may become diluted if the extraction is not performed carefully.
Presently, the most common method of sample extraction/transfer is manually performed in a laboratory where the sample is simply collected using a pipette tip. Particularly, a person will attempt to identify an area having a high concentration of particles, and will simply collect particles by inserting the pipette tip into this location.
However, manual pipette extraction is a slow, tedious endeavor, causing a bottleneck in the attempt to increase the throughput of samples for analytical investigation and experimentation, and also results in inconsistent extraction wherein samples may be undesirably diluted. A further issue in addition to low collection rates and potential dilution of the sample by this process, is that it is not integrated into the concentrator system. The lack of integration is a stumbling block to providing a consistent extraction process.